She’s an enduring legend of country music, but Reba McEntire doesn’t see her exalted status as a free pass for tardiness.

After calling in to her PEOPLE interview earlier this month a mere three minutes late, she apologizes not once, but twice, for running behind.

“Mama and Daddy always said to me, ‘If you tell somebody you’re going to be somewhere at a certain time, you show up,” she says in this week’s issue, on newsstands Friday. “That’s the way I was raised.”

When McEntire, 67, became a mom to her son Shelby (with ex-husband Narvel Blackstock) in 1990, she made sure to pass down those same values she learned growing up in Chockie, Oklahoma.

“When we would play games or cards, I’d never let Shelby win,” she says. “He wouldn’t have learned anything that way. I always told Shelby, ‘I’ll always love you, but I want other people to like you. So don’t be a little jerk. Don’t be a spoiled brat.'”

Those words seem to have resonated with Shelby, 32, as “a lot of people have told me you would never know [he] had been blessed with the life he was given,” McEntire says.

“I’m very proud of him,” she says. “He was a kid who had ADHD and could barely read in school, and now he’s read 10 books this year. He’s always trying to improve and do better. His daddy did a great job too.”

When McEntire had Shelby, she was already a certified superstar. After scoring her first Top 10 country hit “(You Lift Me) Up to Heaven” in 1980, she went on to sell 56 million records, win three Grammys and host the Academy of Country Music Awards a record 16 times.

“Shelby is a gift from God to me,” she says. “We’re very close. I was a very self-centered person to a degree before Shelby. But then there’s a little character who you are given the job to protect and nurture and love and teach, so all the attention’s not on you anymore.”

McEntire adds that she’s thankful she had “a lot of help.”

“I had the best nannies, and I took him on the road with me,” she says. “When I couldn’t, I would fly home after a concert, get him up in the morning, take him to school and pick him up. We’d play until I had to fly out again for a concert that night. I wanted to be with Shelby. Still do.”

In addition to parenting Shelby and her main gig, she headlined the sitcom Reba for seven years while taking other film and TV roles. Currently filming the latest season of the NBC drama Big Sky with her boyfriend Rex Linn in Albuquerque, she’s looking forward to catching up with Shelby and his wife Marissa Branch in Nashville soon.

“Shelby and Marissa are very busy with their jobs, but when I do get to go home to Nashville, we have brunch or a dinner and see them,” McEntire says.

Still realizing new dreams, McEntire says this is “one of the happiest times of my life.”

“I never would’ve thought in a million years I’d be doing an ABC drama at my age, but I am absolutely loving it,” she says. “Now if I can just be a superhero or a supervillain in one of the Marvel movies, that would be the icing on the cake.”